The invention relates generally to an optical communication system and, more particularly, to a power monitoring arrangement suitable for use within a free-space optical switching system.
Optical switching including free-space, beam-steering optics is known. Beam-steering switches are capable of providing a large number of connections within a single stage because each of the individual input and output ports may be configured to a very large number of states. For example, an optical beam from a specified input port may be steered to different angles, thus directing the beam to a large number of output ports.
To ensure that the beam-steering switches direct as much optical energy from an input port to an output port, a training process is utilized whereby optical signals propagated through a switch fabric by various beam-steering switches are measured prior to communication to an input node and after communication to an output node to determine beam attenuation or insertion loss associated with each connection.
A conventional optical power monitor comprises a power tap, which diverts a portion of an optical signal to an optical to electric (O/E) converter such as a p-i-n diode. The p-i-n diode provides a signal that is processed by a trans-impedance amplifier to produce therefrom an output signal suitable for processing by a controller to determine therefrom a power level.
Typically, each of N input ports and M output ports of an Nxc3x97M optical cross connect are associated with a respective optical power monitor. A conventional optical power monitor is provided at each of the N input ports and M output ports to facilitate input and output power measurements and derive therefrom insertion loss data associated with each optical connection within a switch fabric. Unfortunately, the cost of performing such power monitoring is relatively high.
The invention provides a method and an apparatus for measuring optical power within, for example, an optical cross-connect system.
Specifically, a method according to an embodiment of the invention comprises arranging a plurality of light beams according to a parallel configuration; diverting a first portion of the parallel light beams to a first imaging device; propagating a remaining portion of the parallel light beams through a medium; diverting a first portion of the propagated parallel light beams to a second imaging device; and determining an optical loss parameter using imaging data provided by the first and second imaging devices.